To avoid Frontier’s cancellation fee, cancel within 24 1-855- 738-4265 (UShours of booking or ensure your flight is at least 7 days away. 1-855- 738-4265 (US For more details or assistance with cancellations, call Frontier customer care at 1-855- 738-4265 (US. If you cancel Frontier Airlines, refunds depend on fare type. For assistance, contact customer care at 1-855- 738-4265 (US (USA). Non-refundable tickets may receive travel credit. Always check terms before canceling.